[Flax/run_hybrid_clip] Fix duplicating images when captions_per_image exceeds the number of captions, enable truncation

[edugp]

What does this PR do?

Do not duplicate images when the number of captions in an example is smaller than captions_per_image.
Truncate tokens when number of tokens exceeds max_length.

Currently, if an example contains a number of captions smaller than captions_per_image, the dataset will get scrambled, because the image paths are going to be duplicated but the number of captions is not.
For example, if an example contains a single caption and captions_per_image is equal to 2, one caption will be appended to the captions list, but two image path will be appended to the image_paths list. This results in mismatching file_path-caption pairs.
This pull request fixes this issue.

Currently, if a tokenized sentence contains a number of tokens > max_length, the dimensions of inputs within a batch won't match.
This pull request fixes this issue by truncating the tokens to max_length.

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@patil-suraj

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[patil-suraj]

Sorry to only come back to this now.

Great catch @edugp! Thanks a lot for fixing this.